The demand for improved semiconductor device inspection and metrology systems continues to increase. Inspection systems, for example, typically include one or more imaging or scanning sensors, where the one or more imaging or scanning sensors are part of an integrated circuit package. The integrated circuit package may be mounted on a printed circuit board (PCB) or disposed on an interposer mounted on the PCB. High-speed image sensor imaging and scanning requires communication signal paths with controlled impedance, which may place fine design-rule requirements on the PCB.
If multiple integrated circuit packages are mounted directly or indirectly to the PCB, one or more signal lines coupling the integrated circuit packages together may be embedded within the PCB. The one or more signal lines may require high-speed communication channel signal drivers (e.g. optical transceivers). High-speed scanning and imaging sensors can generate a high total data rate, which is sustained for a selected period of inspection time. Although the signal drivers need to be robust, error-free, and capable of sustaining high-speed data rates, the extended sustaining of a high-speed data rate makes significant buffering of the data capturing and transmission difficult.
As imaging sensors are typically fabricated with dedicated integrated circuit packages, the signal drivers may include design constraints (e.g. power dissipation, temperature stability, spacing, and/or fabrication constraints) that limit the performance of the image sensor system and/or degrade the quality of the measurement signal. Additionally, the high density of signals necessary for the high-speed data transfer may place fine design-rule requirements on the PCB trace and/or connector design. As the number of design constraints on the PCB increases, the fabrication of the PCB layers and the assembly of the connectors become increasingly difficult and error-prone. Limitations on the PCB design, even if only a small region of the PCB, may limit the choice of PCB materials and/or increase the cost of the entire PCB.
Where an inspection or metrology system includes one or more arrays of sensors, the conventional approach utilizes either an array of small, modular PCBs or a single main PCB. A single main PCB includes a stable set of power supply and ground connections for all coupled devices, and additionally includes PCB control and logic in a single setup instead of a setup split apart onto multiple boards. Additionally, total component count to fabricate the single main PCB is typically lower than the total component count for an array of small, modular boards. However, a single main PCB is subjected to additional design constraints with high-speed data rates, making fabrication of the single main PCB more difficult and more expensive than an array of small, modular boards.
Therefore, it would be advantageous to provide a system that addresses the shortcomings described above.